Helicopters pick up external loads by connection of a sling to a hook on the helicopter. The cargo sling itself may be attached, or a long line used between the helicopter and the sling. Lines might vary in length from just a few meters to 100 meters or more.
The speed at which a helicopter can fly with a load suspended therebeneath by a cable or the like is limited by the long cable and the load, and the helicopter's innate speed capability. Loads can become unstable, and swing wildly an any direction. Instability and swinging of the load is worse when loads are relatively light. In extreme cases, a load can rise far enough behind the helicopter so that the cable suspending the load may become entangled in the rotors or airframe, causing the helicopter to crash.
Pilots can counteract swinging of a suspended load by visually tracking the load or feeling the load's swing through the helicopter's control system. However, this is distracting to a pilot, and is more difficult to sense and counteract in newer fly-by-wire helicopters. In the instance of computer controlled drone helicopters, the computer cannot feel what the load is doing and needs a way to track the load to counteract its swing.
The same problems related to swinging of a load suspended from a helicopter apply to using a helicopter to engage a load on the ground without having a person on the ground to physically hook the load to the helicopter. When not using a person on the ground, the helicopter must be used to move a hook on the end of a line into the exact right position to snag a load. Without a way to track the hook at the end of the cable or line underneath the helicopter, it may take many attempts to snag the load, which takes time and may be dangerous, particularly in military and combat applications.
Similar circumstances apply to a crane lifting and moving a load. Here, since vision of the operator may be obstructed in a construction situation, it may be impossible for a crane operator to engage a load with a crane hook without assistance.
In order to meet the above and other objectives, the present invention is a method of tracking the end of a line beneath a helicopter, crane, or other means of lifting loads. Its primary purpose is providing information to an operator related to the location of a load suspended by a cable or line so that an operator will know if the load is swinging or begins to swing. In addition, the instant invention allows for manual or automated stabilization of a load at the end of a line, keeping it from swinging dangerously, and to allow a grapple or hook, which may be an automated grapple, at the end of the line to be guided to a load to pick it up autonomously. More particularly, the present invention includes a sensor that detects a beacon attached to or near the end of the line, or near or at the load, and uses a processor to extract the position of the beacon, and thus the end of the line and thus location of a load, grapple or hook, from the sensor data.
Advantageously, the tracking system of the invention includes multiple sources of light in the beacon to improve redundancy and allow for one or more of the light sources to fail or to be hidden by the line connecting the means of lifting to the load.